Check that you are using the correct firmware package. Download latest officially supported Espruino package from https://lab.ruuvi.com/dfu.
Espruino has its own active support forum where many topics are discussed. However, if your problem is clearly related to running Espruino on RuuviTag, please ask on our forum. This is mainly because we don’t want to increase Espruino team’s workload with questions related to third-party hardware platforms.